Closed book
Closed book noun - Something hard to understand or explain.
Usage example: the couple's unorthodox marriage is definitely a closed book to those outside of the relationship
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Synonyms for Closed book
Problem and closed book are semantically related. in puzzle topic. In some cases you can use "Problem" instead a noun phrase "Closed book", when it comes to topics like mystery, brain-teaser.
Problem
Problem noun - Something that requires thought and skill for resolution.
Closed book and problem are semantically related. You can use "Closed book" instead a noun "Problem".
Nearby Words: problematic, problematical
Mutual synonyms
Related pairs
- trouble and closed book
- trouble and problem
- matter and closed book
- matter and problem
- complication and closed book
- complication and problem
- predicament and closed book
- predicament and problem
- question and closed book
- question and problem
- riddle and closed book
- riddle and problem
- difficulty and closed book
- difficulty and problem
Cite this Source
Problem and Closed book. (2016). Retrieved 2026, August 14, from https://thesaurus.plus/related/closed_book/problem
Closed book & Problem. N.p., 2016. Web. 14 Aug. 2026. <https://thesaurus.plus/related/closed_book/problem>.
Problem or Closed book. 2016. Accessed August 14, 2026. https://thesaurus.plus/related/closed_book/problem.
Google Ngram Viewer shows how "closed book" and "problem" have occurred on timeline